The invention relates to coordination catalyst systems and methods of their preparation. Such coordination catalyst systems comprise a support-activator in agglomerate form and dual transition metal catalyst having at least one metallocene and/or constrained geometry pre-catalyst and at least one bi- or tridentate late transition metal pre-catalyst. Coordination catalyst systems, which are usually based on transition metal compounds of Groups 3 to 10 and organometallic compounds of Group 13 of the Periodic Table of the Elements, are exceptionally diverse catalysts which are employed in chemical reactions of and with olefinically unsaturated compounds. Such reactions are embodied in processes for the preparation of olefin polymers by coordination polymerization. The preparation of polyethylene of increased density (high-density polyethylene, HDPE) and of polymers and copolymers of ethylene, propylene or other 1-alkenes is of considerable industrial importance.
The prevailing belief regarding the reaction mechanism of coordination catalysts is that a transition metal compound forms a catalytically active center to which the unsaturated compound, typically olefinically unsaturated, bonds by coordination in a first step. Olefin polymerization takes place via coordination of the monomers and a subsequent insertion reaction into a transition metal-carbon or a transition metal-hydrogen bond.
The presence of organometallic compounds (e.g., organoaluminum compounds such as methylalumoxane) in the coordination catalyst systems or during the catalyzed reaction is thought to be necessary in order to activate the catalyst, or maintain its activity, by reduction and, where appropriate, alkylation or formation of a complex system. These compounds were therefore also called cocatalysts. The compound containing the transition metal atom, which is eventually activated, is typically called the pre-catalyst and after activation, the primary catalyst.
The best known industrially used catalyst systems for coordination polymerization are those of the xe2x80x9cZiegler-Natta catalystxe2x80x9d type and the xe2x80x9cPhillips catalystxe2x80x9d type. The former comprise the reaction product of a metal alkyl or hydride of elements of the first three main groups of the Periodic Table and a reducible compound of a transition metal element of Groups 4 to 7 the combination used most frequently comprising an aluminum alkyl, such as diethylaluminum chloride, and titanium (IV) chloride. More recent highly active Ziegler-Natta catalysts are systems in which the titanium compound is fixed chemically to the surface of magnesium compounds, such as, in particular, magnesium chloride.
More recent developments have focused on single-site catalyst systems. Such systems are characterized by the fact that their metal centers behave alike during polymerization thus making very uniform polymers. Catalysts are judged to behave in a single-site manner when the polymer they make meets some basic criteria (e.g., narrow molecular weight distribution, or uniform comonomer distribution). Thus, the metal can have any ligand set around it and be classified as xe2x80x9csingle-sitexe2x80x9d as long as the polymer that it produces has certain properties.
Included within single-site catalyst systems are metallocene catalysts and constrained geometry catalysts. A xe2x80x9cmetallocenexe2x80x9d is conventionally understood to mean a metal (e.g., Zr, Ti, Hf, Sc, Y, V or La) complex that is bound to at least one cyclopentadienyl (Cp) rings, or derivatives thereof, such as indenyl, tetrahydroindenyl, fluorenyl and mixtures. In addition to the two Cp ligands, other groups can be attached to the metal center, most commonly halides and alkyls. The Cp rings can be linked together (so-called xe2x80x9cbridged metallocenexe2x80x9d structure), as in most polypropylene catalysts, or they can be independent and freely rotating, as in most (but not all) metallocene-based polyethylene catalysts. The defining feature is the presence of at least one and preferably two Cp ligands or derivatives. Metallocene catalysts can be employed either as so-called xe2x80x9cneutral metallocenesxe2x80x9d in which case an alumoxane, such as methylalumoxane, is used as a co-catalyst, or they can be employed as so-called xe2x80x9ccationic metallocenesxe2x80x9d which are neutral metallocenes which have been activated, e.g., ionized, by an activator such that the active catalyst species incorporates a stable and loosely bound non-coordinating anion as a counter ion to a cationic metal metallocene center. Cationic metallocenes are disclosed in U.S. Pat. Nos. 5,064,802; 5,225,500; 5,243,002; 5,321,106; 5,427,991; and 5,643,847; and EP 426 637 and EP 426 638, the disclosures of which are incorporated herein by reference.
xe2x80x9cConstrained geometryxe2x80x9d is a term that refers to a particular class of organometallic complexes in which the metal center is bound by only one modified Cp ring or derivative. The Cp ring is modified by bridging to a heteroatom such as nitrogen, phosphorus, oxygen, or sulfur, and this heteroatom also binds to the metal site. The bridged structure forms a fairly rigid system, thus the term xe2x80x9cconstrained geometryxe2x80x9d. By virtue of its open structure, the constrained geometry catalyst can produce resins having long chain branching that are not possible with normal metallocene catalysts. Constrained geometry catalysts are disclosed in U.S. Pat. Nos. 5,064,802 and 5,321,106. Constrained geometry catalysts can also be employed in neutral or cationic form and use methylalumoxane or ionization activators respectively in the same fashion as metallocenes.
Still more recently, late transition metal (e.g., Fe, Co, Ni, or Pd) bidentate and tridentate catalyst systems have been developed. Representative disclosures of such late transition metal catalysts are found in U.S. Pat. No. 5,880,241 and its divisional counterparts U.S. Pat. Nos. 5,880,323; 5,866,663; 5,886,224; and 5,891,963, and PCT International Application Nos. PCT/US98/00316; PCT/US97/23556; PCT/GB99/00714; PCT/GB99/00715; and PCT/GB99/00716.
Both the single site and late transition metal pre-catalysts typically require activation to form a cationic metal center by an organometal Lewis acid (e.g., methylalumoxane (MAO)) (characterized as operating through a hydrocarbyl abstraction mechanism). Such activators or cocatalysts are pyrophoric, and are typically employed in quantities which are multiples of the catalyst. Attempts to avoid such disadvantages have led to the development of borane (e.g., trispentaflurophenylborane) and borate (e.g., ammonium tetrakispentaflurophenylborate) activators which are non-pyrophoric but more expensive to manufacture and require pyrophoric reagents to make the same. These factors complicate the development of heterogeneous versions of such catalyst systems in terms of meeting cost and performance targets.
Use of these catalysts and related types in various polymerization processes can give products sometimes having different properties. In the case of olefin polymers, which are generally known to be important as materials, the suitability for particular applications depends, on the one hand, on the nature of the monomers on which they are based and on the choice and ratio of comonomers and the typical physical parameters which characterize the polymer, such as average molecular weight, molecular weight distribution, degree of branching, degree of crosslinking, crystallinity, density, presence of functional groups in the polymer and the like, and on the other hand, on properties resulting from the process, such as content of low molecular weight impurities and presence of catalyst residues, and, last but not least, on costs.
In addition to realizing desired product properties, other factors are decisive for evaluating the efficiency of a coordination catalyst system, such as the activity of the catalyst system, that is to say, the amount of catalyst required for economic conversion of a given amount of olefin, the product conversion per unit time and the product yield. The stability and ease of handling of the catalyst or its components is another factor that affects the choice of commercial embodiments thereof. Practically all known coordination catalysts are extremely sensitive to air and moisture to varying degrees. Coordination catalysts are typically reduced in their activity or irreversibly destroyed by exposure to (atmospheric) oxygen and/or water. Most Ziegler-Natta and metallocene catalysts, for example, deactivate spontaneously on exposure to air and become unusable. Most coordination catalysts must therefore typically be protected from exposure to air and moisture during preparation, storage and use, which of course makes handling difficult and increases the expense of their manufacture.
A still further factor to be considered is the ability to utilize the coordination catalyst as a heterogeneous catalyst system. The advantages of a heterogeneous catalyst system are more fully realized in a slurry polymerization process. More specifically, slurry polymerizations are often conducted in a reactor wherein monomer, catalysts, and diluent are continuously fed into the reactor. The solid polymer that is produced (typically in the form of polymer xe2x80x9cfluffxe2x80x9d) is not dissolved in the diluent and is allowed to settle out before being periodically withdrawn form the reactor. In this kind of polymerization, factors other than activity and selectivity, which are always present in solution processes, become of paramount importance. For example, in the slurry process it is desired to have a supported catalyst which produces relatively high bulk density polymer. If the bulk density is too low, the handling of the solid polymer becomes impractical. It is also an advantage to have the polymer formed as uniform, spherical particles that are relatively free of fines. Although fines can have a high bulk density, they also do not settle as well as larger particles and they present additional handling problems with the later processing of the polymer fluff. Furthermore, slurry polymerization processes differ in other fundamental ways from the typical solution polymerization processes. The latter requires higher reaction temperatures ( greater than 130xc2x0 C.) and pressures ( greater than 450 psi) and often results in lower molecular weight polymers. The lower molecular weight is attributed to the rapid chain-termination rates under such reaction conditions. Although lowering the reaction temperature and/or pressure, or changing molecular structure of the metallocene catalyst can produce higher molecular weight polymer in a solution process, it becomes impractical to process the resulting high molecular weight polymers in the downstream equipment due to the high solution viscosity. In contrast, a slurry reaction process overcomes many of the above disadvantages by simply operating at lower temperature ( less than 100xc2x0 C.). As a result, a higher molecular weight polymer with a uniform particle size and morphology can be routinely obtained. It is also advantageous to carry out slurry reactions with sufficiently high polymerization efficiencies such that residues from the polymerization catalysts do not have to be removed from the resulting polymers.
The above-discussed advantages of slurry polymerization processes provide incentive for developing coordination catalysts in heterogeneous form. Thus far, gas phase polymerization processes are only practical with a heterogeneous catalyst system.
Finally, evaluation of a coordination catalyst system must include process considerations that influence the morphology (e.g., bulk density) of the resulting polymer, the environmental friendliness of the process, and the avoidance of reactor fouling. Thus, there has been a continuing search to develop a coordination catalyst system, preferably a heterogeneous coordination catalyst system, which demonstrates high catalyst activity, is free of reactor fouling, produces polymer products having good morphology while simultaneously being process friendly (e.g., easy to make) and inexpensive to make. There has also been a particular need to discover catalyst systems that are adapted more readily to cope with the propensity to deactivate and/or are less hazardous in use. The present invention was developed in response to these needs.
International application No. PCT/US97/11953 (International Publication No. WO 97/48743) is directed to frangible, spray dried agglomerate catalyst supports of silica gel, which possess a controlled morphology of microspheroidal shape, rough scabrous appearance, and interstitial void spaces which penetrate the agglomerate surface and are of substantially uniform size and distribution. The agglomerates also possess a 1-250 micron particle size, 1-1000 m2/g surface area, and an Attrition Quality Index (AQI, defined in the publication) of at least 10. The agglomerates are derived from a mixture of dry milled inorganic oxide particles, e.g., silica gel and optionally but preferably wet milled inorganic oxide particles, e.g., silica gel particles (which preferably contain colloidal particles of less than 1 micron particle size), slurried in water for spray drying. The high AQI assures that the agglomerates are frangible and that the polymerization performance is improved. The controlled morphology is believed to permit the constituent particles of the agglomerates to be more uniformly impregnated or coated with conventional olefin polymerization catalysts. Clay is not disclosed as suitable metal oxide. The teaching of the above cited reference, particularly with regard to the preparation of a support having defined AQI characteristics, is incorporated herein in its entirety by reference.
U.S. Pat. No. 5,633,419 discloses the use of spray dried silica gel agglomerates- as supports for Ziegler-Natta catalyst systems.
U.S. Pat. No. 5,395,808 discloses bodies made by preparing a mixture of ultimate particles of bound clay, with one or more optional ingredients such as inorganic binders, extrusion or forming aids, burnout agents or forming liquid, such as water. Preferably the ultimate particles are formed by spray drying. Suitable binders include silica when Kaolin clay is used as the inorganic oxide. The bodies are made from the ultimate particles and useful methods for forming the bodies include extrusion, pelletization, balling, and granulating. Porosity is introduced into the bodies during their assembly from the ultimate particles, and results primarily from spaces between the starting particles. The porous bodies are disclosed to be useful as catalyst supports. See also U.S. Pat. Nos. 5,569,634; 5,403,799; and 5,403,809; and EP 490 226 for similar disclosures.
U.S. Pat. No. 5,362,825 discloses olefin polymerization catalysts produced by contacting a pillared clay with a Ziegler-Natta catalyst, i.e., a soluble complex produced from the mixture of a metal dihalide with at least one transition metal compound in the presence of a liquid diluent. The resulting mixture is in turn contacted with an organoaluminum halide to produce the catalyst.
U.S. Pat. No. 5,807,800 is directed to a supported metallocene catalyst comprising a particulate catalyst support, such as a molecular sieve zeolite, and a stereospecific metallocene, supported on the particulate support and incorporating a metallocene ligand structure having two sterically dissimilar cyclopentadienyl ring structures coordinated with a central transition metal atom. At column 4 of the background discussion, it is disclosed that cationic metallocenre""s which incorporate a stable non-coordinating anion normally do not require the use of alumoxane.
EP 426,638 discloses a process for polymerizing olefins which comprises mixing an aluminum alkyl with the olefin to be polymerized, preparing the metallocene catalyst, and mixing the catalyst with the aluminum alkyl-olefin mixture without a methylaluminoxane co-catalyst. The metallocene catalyst is an ion pair formed from a neutral metallocene compound and an ionizing compound such as triphenylcarbenium tetrakis (pentafluorophenyl) borate.
U.S. Pat. No. 5,238,892 discloses the use of undehydrated silica as a support for metallocene and trialkylaluminum compounds.
U.S. Pat. No. 5,308,811 discloses an olefin polymerization catalyst obtained by contacting (a) a metallocene-type transition metal compound, (b) at least one member selected from the group consisting of clay, clay minerals, ion exchanging layered compounds, diatomaceous earth, silicates and zeolites, and (c) an organoaluminum compound. Component (b) may be subjected to chemical treatment, which, for example, utilizes ion exchangeability to substitute interlaminar exchangeable ions of the clay with other large bulky ions to obtain a layered substance having the interlaminar distance enlarged. Such bulky ions function as pillars, supporting the layered structure, and are therefore called pillars. Guest compounds, which can be intercalated, include cationic inorganic compounds derived from such materials as titanium tetrachloride and zirconium tetrachloride. SiO2 may be present during such intercalation of guest compounds. The preferred clay is montmorillonite. Silica gel is not disclosed as a suitable component (b).
U.S. Pat. No. 5,714,424 discloses a method of forming a polyolefin composite catalyst particle comprising two or more distinct supported catalyst components in a single catalyst particle in order to polymerize olefins to a polyolefin having two or more melt indices. The catalyst types are selected from chrome-silica, Ziegler-Natta and metallocene catalysts. The catalyst components can be sized by co-milling and the particles isolated from a solvent preparation step by spray drying. The inventors describe multiple catalyst components but do not disclose an agglomerated support or such a support including an integrated ion containing layered material having Lewis acidity for activating the catalyst components. In fact, it is stated that the composition of the invention of the reference xe2x80x9cdoes not depend in any manner on the pore structure of the support. The only requirement is that the individual (catalyst) components have different melt index potentials . . . and that have approximately the same activity.xe2x80x9d (column 3, lines 30-35). The supports used in the examples were prepared using one or more of washed filter cake silica; dried, coarse milled and washed silica hydrogel; and dried, sized and calcined silica/titania cogel.
U.S. Pat. No. 5,753,577 discloses a polymerization catalyst comprising a metallocene compound, a co-catalyst such as proton acids, ionized compounds, Lewis acids and Lewis acidic compounds, as well as clay mineral. The clay can be modified by treatment with acid or alkali to remove impurities from the mineral and possibly to elute part of the metallic cations from the crystalline structure of the clay. Examples of acids which can effect such modification include Bronsted acids such as hydrochloric, sulfuric, nitric and acetic acids. The preferred modification of the clay is accomplished by exchanging metallic ions originally present in the clay with specific organic cations such as aliphatic ammonium cations, oxonium ions, and onium compounds such as aliphatic amine hydrochloride salts. Such polymerization catalysts may optionally be supported by fine particles of SiO2, Al2O3, ZrO2, B2O3, CaO, ZnO, MgCl2, CaCl2, and mixtures thereof. (Col. 3, line 48; Col. 21, line 10 et seq.). The fine particle support may be of any shape preferably having a particle size in the range of 5-200 microns, and pore size ranges of from 20-100 xc3x85. Use of metal oxide support is not described in the examples.
U.S. Pat. No. 5,399,636 discloses a composition comprising a bridged metallocene that is chemically bonded to an inorganic moiety such as clay or silica. The olefin polymerization catalyst system is disclosed as including such standard activators or cocatalysts as organoborates and organoaluminoxanes; methylaluminoxanes are preferred (column 8, lines 38 to column 9, line 40) and its use is illustrated in the sole polymerization working example (VI). Silica is illustrated in the working examples as a suitable support, but not clay.
EP 849 292 discloses an olefin polymerization catalyst consisting essentially of a metallocene compound, a modified clay compound, and an organoaluminum compound. The modification of the clay is accomplished by reaction with specific amine salts such as a proton acid salt obtained by the reaction of an amine with a proton acid (hydrochloric acid). The specifically disclosed proton acid amine salt is hexylamine hydrochloride. The modification of the clay results in exchange of the ammonium cation component of the proton acid amine salt with the cations originally present in the clay to form the mineral/organic ion complex.
U.S. Pat. No. 5,807,938 discloses an olefin polymerization catalyst obtained by contacting a metallocene compound, an organometallic compound, and a solid catalyst component comprising a carrier and an ionized ionic compound capable of forming a stable anion on reaction with the metallocene compound. Suitable carriers disclosed include inorganic compounds or organic polymeric compounds. The inorganic compounds include inorganic oxides, such as alumina, silica, silica-alumina, silica magnesia; clay minerals; and inorganic halides. The ionized ionic compound contains an anionic component and a cationic component. The cationic component preferably comprises a Lewis Base functional group containing an element of the Group 15 or 16 of the Periodic Table such as ammonium, oxionium, sulfonium, and phosphonium, cations. The cation component may also contain a functional group other than Lewis Base function groups, such as carbonium, tropynium, and a metal cation. The anion component includes those containing a boron, aluminum, phosphorous or antimony atom, such as an organoboron, organoaluminum, organophosphorous, and organoantimony anions. The cationic component is fixed on the surface of the carrier. Only silica or chlorinated silica are employed in the working examples as a carrier. In many examples, the silica surface is modified with a silane.
U.S. Pat. No. 5,830,820 discloses an olefin polymerization catalyst comprising a modified clay mineral, a metallocene compound, and an organoaluminum compound. The clay mineral is modified with a compound capable of introducing a cation into the layer interspaces of the clay mineral. Suitable cations which are inserted into the clay include those having a proton, namely, Bronsted acids such trimethylammonium, as well as carbonium ions, oxonium ions, and sulfonium ions. Representative anions include chlorine ion, bromide ion, and iodide ion.
EP 881 232 is similar to U.S. Pat. No. 5,830,820, except that the average particle size of the clay is disclosed as being less than 10 microns.
EP 849 288 discloses an olefin polymerization catalyst consisting essentially of a metallocene compound, an organoaluminum compound, and a modified clay compound. The clay is modified by contact with a proton acid salt of certain specific amine compounds, such as hexylamine chloride.
JP Kokai Patent HEI 10-338516 discloses a method for producing a metallic oxide intercalated in a clay mineral which comprises swelling and diluting the clay mineral, having a laminar structure, with water to form a sol; adding an organometallic compound to an aqueous solution containing organic acid to form a sol that contains the metallic compound; mixing the swelling clay mineral sol with the metallic compound containing sol and agitating to intercalate the metallic compound between the layers in the swollen clay mineral; and washing, dehydrating, drying and roasting the clay mineral that has the metallic compound intercalated therein. Suitable metallic oxides include those of titanium, zinc, iron, and tin.
U.S. Pat. No. 4,981,825 is directed to a dried solid composition comprising clay particles and inorganic metal oxide particles substantially segregated from the clay particles. More specifically, the metal oxide particles are sol particles which tend to fuse upon sintering. Consequently, by segregating the sol particles with smectite-type clay particles, fusion of the sol particles is reduced under sintering conditions thereby preventing a loss of surface area. The preferred metal oxide is colloidal silica having an average particle size between 40 and 800 angstroms (0.004 and 0.08 microns), preferably 40 and 80 angstroms. The ratio of the metal oxide to clay is between about 1:1 to 20:1, preferably 4:1 to 10:1. The end product is described at Column 3, line 50 et seq. as sol particle-clay composites in which the clay platelets inhibit aggregation of the sol particles. Such products are made up entirely of irregular sol-clay networks in which the clay platelets are placed between the sol particles. The result is a composite with very high surface area, and ability to retain such high surface area at elevated temperatures. This arrangement is also distinguished from intercalation of the clay by the silica. The subject compositions are disclosed in the abstract to be useful for catalytic gaseous reactions and removal of impurities from gas streams. Specific catalysts systems are not disclosed.
U.S. Pat. No. 4,761,391 discloses delaminated clays whose x-ray detraction patterns do not contain a distinct first order reflection. Such clays are made by reacting synthetic or natural swelling clays with a pillaring agent selected from the group consisting of polyoxymetal cations, mixtures of polyoxymetal cations, colloidal particles comprising alumina, silica, titania, chromia, tin oxide, antimony oxide or mixtures thereof, and cationic metal clusters comprising nickel, molybdenum, cobalt, or tungsten. The resulting reaction product is dried in a gaseous medium, preferable by spray drying. The resulting acidic delaminated clays may be used as the active component of cracking and hydroprocessing catalysts. The ratio of clay to pillaring agent is disclosed to be between about 0.1 and about 10. To obtain the delaminated clay, a suspension of swelling clay, having the proper morphology, e.g., colloidal particle size, is mixed with a solution or a suspension of the pillaring agent at the aforedescribed ratios. As the reactants are mixed, the platelets of clay rapidly sorb the pillaring agent producing a flocculated mass comprised of randomly oriented pillared platelet aggregates. The flocculated reaction product or gel is then separated from any remaining liquid by techniques such as centrifugation filtration and the like. The gel is then washed in warm water to remove excess reactants and then preferably spray dried. The pillaring agent upon heating is converted to metal oxide clusters which prop apart the platelets of the clay and impart the acidity which is responsible for the catalytic activity of the resultant delaminated clay. The x-ray defraction pattern of such materials contains no distinct first order of reflection which is indicative of platelets randomly oriented in the sense that, in addition to face-to-face linkages of platelets, there are also face-to-edge and edge-to-edge linkages. The utilities described at Column 8, Lines 55 et seq. include use as components of catalyst, particularly hydrocarbon conversion catalysts, and most preferably as components of cracking and hydrocracking catalysts. This stems from the fact that because the clay contains macropores as well as micropores, large molecules that normally cannot enter the pores of zeolites will have access to the acid sites in the delaminated clays making such materials more efficient in cracking of high molecular weight hydrocarbon constituents. (See also U.S. Pat. No. 5,360,775.)
U.S. Pat. No. 4,375,406 discloses compositions containing fibrous clays and precalcined oxides prepared by forming a fluid suspension of the clay with the precalcined oxide particles, agitating the suspension to form a co-dispersion, and shaping and drying the co-dispersion. Suitable fibrous clays include aluminosilicates, magnesium silicates, and aluminomagnesium silicates. Examples of suitable fibrous clays are attapulgite, playgorskite, sepiolite, haloysite, endellite, chrysotile asbestos, and imogolite. Suitable oxides include silica. The ratio of fibrous clay to precalcined oxide is disclosed to vary from 20:1 to 1:5 by weight.
Additional patents which disclose intercalated clays are U.S. Pat. Nos. 4,629,712 and 4,637,992. Additional patents which disclose pillared clays include U.S. Pat. Nos. 4,995,964 and 5,250,277.
A paper presented at the MetCon ""99 Polymers in Transition Conference in Houston, Tex., on June 9-10, 1999, entitled xe2x80x9cNovel Clay Mineral-Supported Metallocene Catalysts for Olefin Polymerizationxe2x80x9d by Yoshinor Suga, Eiji Isobe, Toru Suzuki, Kiyotoshi Fujioka, Takashi Fujita, Yoshiyuki Ishihama, Takehiro Sagae, Shigeo Go, and Yumito Uehara discloses olefin polymerization catalysts comprising metallocene compounds supported on dehydrated clay minerals optionally in the presence of organoaluminum compounds. At page 5 it is disclosed that catalysts prepared with fine clay mineral particles have had operational difficulties such as fouling which make them unsuitable for slurry and gas phase processes. Thus, a granulation method was developed to give the clay minerals a uniform spherical shape. The method for producing this spherical shape is not disclosed.
PCT International Application No. PCT/US96/17140, corresponding to U.S. application Ser. No. 562,922, discloses a support for metallocene olefin polymerizations comprising the reaction product of an inorganic oxide comprising a solid matrix having reactive hydroxyl groups or reactive silane functionalized derivatives of hydroxyl groups on the surface thereof, and an activator compound. The activator compound comprises a cation which is capable of reacting with the metallocene compound to form a catalytically active transition metal complex and a compatible anion containing at least one substituent able to react with the inorganic oxide matrix through residual hydroxyl functionalities or through the reactive silane moiety on the surface thereof. The representative example of a suitable anion activator is tris(pentafluorophenyl)(4-hydroxyphenyl)borate. Suitable inorganic oxides disclosed include silica, alumina, and aluminosilicates.
U.S. Pat. No. 5,880,241 discloses various late transition metal bidentate catalyst compositions. At column 52, lines 18 et seq., it is disclosed that the catalyst can be heterogenized through a variety of means including the use of heterogeneous inorganic materials as non-coordinating counter ions. Suitable inorganic materials disclosed include aluminas, silicas, silica/aluminas, cordierites, clays, and MgCl2 but mixtures are not disclosed. Spray drying the catalyst with its associated non-coordinating anion onto a polymeric support is also contemplated. Examples 433 and 434 employ montmorillonite clay as a support but polymer morphology is not disclosed for these examples.
PCT International Application No. PCT/US97/23556 discloses a process for polymerizing ethylene by contact with Fe or Co tridentate ionic complex formed either through alkylation or abstraction of the metal alkyl by a strong Lewis acid compound, e.g., MAO, or by alkylation with a weak Lewis acid, e.g., triethylaluminum and, subsequent abstraction of the resulting alkyl group on the metal center with a stronger Lewis acid, e.g., B(C6F5)3. The Fe or Co tridentate compound may be supported by silica or alumina and activated with a Lewis or Bronsted acid such as an alkyl aluminum compound (pg. 19, line 1 et seq.). Acidic clay (e.g., montmorillonite) may function as the support and replace the Lewis or Bronsted acid. Examples 43-45 use silica supported MAO, and Example 56 employs dehydrated silica as a support for the Co complex. Polymer morphology is not discussed.
PCT International Application No. PCT/US98/00316 discloses a process for polymerizing propylene using catalysts similar to the above discussed PCT-23556 application.
U.S. application Ser. No. 09/166,545, filed Oct. 5, 1998, now U.S. Pat. No. 6,184,171, by Keng-Yu Shih, an inventor of the present application, discloses a supported late transition metal bidentate or tridentate catalyst system containing anion and cation components wherein the anion component contains boron, aluminum, gallium, indium, tellurium and mixtures thereof covalently bonded to an inorganic support (e.g. SiO2) through silane derived intermediates such as a silica-tethered anilinium borate.
PCT International Published Application WO 99/40131 discloses homopolymerization or copolymerization of ethylene with an alphaolefin in the presence of a silica/alumina supported catalyst. The polymer is said to contain less than 12 wt. % of polymer having molecular weight less than 5000 g/mole. Such polymers are produced using a particulate modified catalyst in a single polymerization process and preferably in a single polymerization stage. The modified catalyst is a mixture of preferably bivalent chromium oxide catalyst and a metallocene-alumoxane single site catalyst, each chemically bonded to the support. The polymers produced are said to have a molecular weight distribution breadth that is broader than a typical metallocene polymer but narrower than that produced using a chromium based catalyst and having a combination of high melt strength, low melt viscosity and good extrusion processability.
U.S. application Ser. No. 09/431,803 filed on Nov. 1, 1999 by Keng-Yu Shih discloses the use of silica agglomerates as a support for transition metal catalyst systems employing specifically controlled (e.g., very low) amounts of non-abstracting aluminum alkyl activators. U.S. application Ser. No. 09/431,771 filed on Nov. 1, 1999, now U.S. Pat. No. 6,399,535, by Keng-Yu Shih et al. discloses a coordination catalyst system comprising a bidentate or tridentate pre-catalyst transition metal compound, at least one support-activator, e.g., spray dried silica/clay agglomerate, and optionally an organometallic compound and methods.
U.S. application Ser. No. 09/432,008 filed on Nov. 1, 1999, now U.S. Pat. No. 6,559,090, by Keng-Yu Shih et al. discloses a coordination catalyst system comprising a metallocene or constrained geometry pre-catalyst transition metal compound, at least one support-activator, e.g., spray dried silica/clay agglomerate, and optionally an organometallic compound and methods for their preparation.
U.S. application Ser. No. 60/287,601, filed on even date with the present application discloses a catalyst composition composed of a support-agglomerate comprising i) at least one inorganic oxide component, and ii) at least one ion-containing layered component, and the agglomerate has chromium atoms covalently bonded to oxygen atoms of the inorganic oxide.
U.S. application Ser. No. 60/287,607, filed on even date with the present application discloses a process for forming a catalyst composition comprising substantially simultaneously contacting at least one bidentate ligand compound or at least one tridentate ligand compound or mixtures thereof with a transition metal compound and with a support agglomerate comprising i) at least one inorganic oxide component, and ii) at least one ion-containing layered component. The reference further is directed to the resultant catalyst composition for which the support agglomerate functions as the activator for the catalyst system.
U.S. application Ser. No. 60/287,617, filed on even date with the present application discloses a catalyst composition composed of a support-agglomerate comprising i) at least one inorganic oxide component, and ii) at least one ion-containing layered component and the agglomerate has chromium atoms covalently bonded to oxygen atoms of the inorganic oxide. The agglomerate provides a support activator for at least one coordination catalyst comprising a bidentate or tridentate pre-catalyst transition metal compound.
U.S. application Ser. No. 60/287,600, filed on even date with the present application discloses a process for forming a catalyst composition comprising substantially simultaneously contacting at least one bidentate ligand compound or at least one tridentate ligand compound or mixtures thereof with a transition metal compound and with a support agglomerate comprising i) at least one inorganic oxide component, and ii) at least one ion-containing layered component and the agglomerate has chromium atoms covalently bonded to oxygen atoms of the inorganic oxide. The reference is further directed to the resultant catalyst composition for which the support agglomerate functions as the activator for the catalyst system.
The present invention relies on the discovery that certain agglomerate composite particles of an inorganic oxide (e.g., silica) and an ion exchanging layered compound (e.g., clay) are believed to possess enhanced dispersion and accessibility of their Lewis acidity which renders them extremely proficient support-activators for metallocene, constrained geometry and bi- and tridentate transition metal compound pre-catalysts, particularly when such pre-catalyst compounds are used in combinations based on (A) at least one metallocene or constrained geometry transition metal compound and (B) at least one bi- or tridentate transition metal compound. More specifically, it is believed that the agglomerate particles incorporate the ionizable clay particles in such a way that their known Lewis acidity is more uniformly dispersed throughout the particle while simultaneously being made more accessible for interaction with the mixed pre-catalyst compounds. It is believed that this permits the support-activator effectively to activate, e.g., ionize, the pre-catalysts when in a pre-activated (e.g., ionizable) state as well as to support the active catalyst during polymerization. This eliminates the need to use additional ionizing agents such as borane/borate, and MAO activators which are expensive, and introduce added complexity to the system. In contrast, the support-activator is inexpensive, environmentally friendly, and easy to manufacture. Furthermore, polymers produced by the use of such mixed transition metal pre-catalysts can exhibit a broad molecular weight distribution.
The present invention relies on the further discovery that pre-activation of the pre-catalyst is very sensitive to the level of certain organometallic compounds and is induced by low amounts of the same. This further reduces the catalyst system costs, and eliminates the need for expensive MAO or borane/borate activators of the prior art while simultaneously achieving extremely high activity.
A still further aspect of the discovery of the present invention is that the support-activator apparently immobilizes the pre-catalyst by adsorption and/or absorption, preferably by chemadsorption and/or chemabsorption from a slurry of the same without any special impregnation steps, which slurry can actually be used directly for the slurry polymerization of unsaturated monomers, e.g., olefins. The resulting polymer morphology is indicative of a heterogeneous polymerization which is consistent with the observation that the support-activator is readily impregnated by the pre-catalyst such that it is believed to react with the same. Moreover, the microspheroidal morphology of the catalyst system coupled with the immobilization of the active catalyst therein is believed to contribute to the extremely desirable observed polymer morphology because it reduces or prevents reactor fouling, reduces or eliminates polymer fines and results in production of a polymer that exhibits a high bulk density. The catalyst system can be employed as a slurry or dry powder.
A still even further aspect of the discovery of the present invention is the functional interrelationship which exists between the weight ratio of inorganic oxide to layered material, the calcination temperature, and the amount of organoaluminum compound on the one hand, and the catalyst activity on the other hand, such that these variables can be controlled to exceed the activity of the same pre-catalyst supported and/or activated by the inorganic oxide alone, or the layered material (e.g., clay) alone, while simultaneously producing good polymer morphology.
Accordingly, in one aspect of the invention there is provided a coordination catalyst system, preferably a heterogeneous coordination catalyst system, comprising:
(I) as a pre-catalyst, at least one each of a Group (1) material and a Group (2) material wherein said Group (1) material, is at least one metallocene or constrained geometry transition metal compound capable of (i) being activated upon contact with a support-activator (II) or (ii) being converted, upon contact with an organometallic compound, to an intermediate capable of being activated upon contact with said support-activator (II), wherein the transition metal is at least one metal selected from the group consisting of Groups 3, 4 and the Lanthanide metals of the Periodic Table of Elements; and wherein said Group (2) material is at least one non-metallocene, non-constrained geometry, bidentate transition metal compound or tridentate transition metal compound capable of (i) being activated upon contact with said support-activator (II) or (ii) being converted, upon contact with an organometallic compound, to an intermediate capable of being activated upon contact with said support-activator (II), wherein the transition metal is at least one member selected from Groups 3 to 10 of the Periodic table; in intimate contact with
(II) catalyst support-activator agglomerate particles comprising a composite of (A) at least one inorganic oxide component selected from SiO2, Al2O3, MgO, AlPO4, TiO2, ZrO2, or Cr2O3 and (B) at least one ion containing layered material having interspaces between the layers, said support-activator having sufficient Lewis acidity, to activate said pre-catalyst when said pre-catalyst is in contact with said support-activator, said layered material having a cationic component and an anionic component, wherein said cationic component is present within the interspace of the layered material, said layered material being intimately dispersed with said inorganic oxide component within the agglomerate particles in an amount sufficient to provide a coordination catalyst system having the ability to polymerize at least one unsaturated monomer; wherein the amount of the pre-catalyst and support-activator which is in intimate contact is sufficient to provide a ratio of micromoles of pre-catalyst to grams of support-activator of from about 5:1 to about 500:1.
In another aspect of the present invention, there is provided a process for making the above catalyst system which comprises:
(I) agglomerating to form particles of a support-activator:
(A) at least one inorganic oxide component selected from SiO2, Al2O3, MgO, AlPO4, TiO2, ZrO2, or Cr2O3 with
(B) at least one ion containing layered material having interspaces between the layers, said support-activator having sufficient Lewis acidity to activate the pre-catalyst compound of (II) when the pre-catalyst is in contact with the support-activator, said layered material having a cationic component and an anionic component, wherein said cationic component is present within the interspace of the layered material, said layered material being intimately dispersed with said inorganic oxide component within the agglomerate particles in amounts sufficient to provide a coordination catalyst system having the ability to polymerize said at least one unsaturated monomer;
(II) providing as a pre-catalyst, at least one each of a Group (1) material and a Group (2) material wherein said Group (1) material is at least one metallocene or constrained geometry transition metal compound capable of (i) being activated upon contact with the support-activator, or (ii) being converted, upon contact with an organometallic compound, to an intermediate capable of being activated upon contact with said support-activator, wherein the transition metal is at least one metal selected from the group consisting of Groups 3, 4 and the Lanthanide metals of the Periodic Table of Elements; and wherein said Group (2) material is at least one non-metallocene, non-constrained geometry, bidentate transition metal compound or tridentate transition metal compound capable of (i) being activated upon contact with said support-activator or (ii) being converted, upon contact with an organometallic compound, to an intermediate capable of being activated upon contact with said support-activator, wherein the transition metal is at least one member selected from Groups 3 to 10 of the Periodic table;
(III) contacting each pre-catalyst component Group (1) and Group (2) materials, separately or together, with the support-activator, in the presence of at least one inert liquid hydrocarbon in a manner sufficient to provide in the liquid hydrocarbon, a ratio of micromoles of pre-catalyst to grams of support-activator of from about 5:1 or to about 500:1, and to cause at least one of absorption and adsorption of the pre-catalyst by the support-activator.